Malignant neoplasm of cerebral ventricle

This code signifies a primary cancerous tumor originating within the cerebral ventricles, excluding the fourth ventricle. These tumors arise from the ependymal lining or choroid plexus and can obstruct cerebrospinal fluid flow, leading to hydrocephalus.

Apply this code when documentation explicitly states a malignant neoplasm located in any cerebral ventricle other than the fourth. This diagnosis is typically confirmed through imaging studies (e.g., MRI, CT) and often biopsy.

• Always specify the exact ventricular location if known, as some sites have more specific codes.
• Distinguish between primary malignant neoplasms and metastatic lesions to the ventricles.
• Refer to the Excludes1 note to avoid co-coding with C71.7 for fourth cerebral ventricle involvement.